This EventType is used by a Server to indicate that a significant change has occurred in the Server or in the subsystem below the Server that may or does invalidate the Condition state of a Subscription. Its representation in the AddressSpace is formally defined in Table 135.

Table 135 – RefreshRequiredEventType definition

Attribute	Value
BrowseName	RefreshRequiredEventType
IsAbstract	True
References	NodeClass	BrowseName	DataType	TypeDefinition	ModellingRule
Subtype of the SystemEventType defined in 10000-5, i.e. it has HasProperty References to the same Nodes.
ConformanceUnits
A & C Refresh
A & C Refresh2

When a Server detects an Event queue overflow, it shall track if any Condition Events have been lost, if any Condition Events were lost, it shall issue a RefreshRequiredEventType Event to the Client after the Event queue is no longer in an overflow state.